1. Field of the Invention
The invention relates to a liquid crystal display field, and more particularly, to a pixel structure, a display panel, and a liquid crystal display.
2. Description of the Prior Art
As the progress of the information society, demands for displays are growing rapidly. In order to meet these demands, several types of flat displays are introduced. For example, LCD (liquid crystal display), PDP (plasma display panel), and OLED (organic light-emitting diode) displays are developed. In these flat displays, LCD display is widely utilized because of its low weight, small volume, low power consumption.
TN (twisted nematic) type or STN (super twisted nematic) type LCD displays have some problems of low contrasts or small view angle. In order to solve the problems, IPS (in plan switch) display mode and VA (vertical alignment) display mode are developed to provide a wide view angle.
For IPS display mode, it has very good wide view angle effect. However, in order to achieve a better display effect, the demands in the friction procedure of the manufacturing process are strict. This highly limits the tolerance of frictions. In mass productions, related problems may occur.
For VA display mode, as shown in FIG. 1a and FIG. 1b, the LCD display is composed of an upper substrate 11, a lower substrate 12, and negative liquid crystals 14 embedded between the two substrates. Transparent conducting layers (ITO) 13 are set on the inner sides of the two substrates 11 and 12, and form a vertical electrical field. The dielectric constant of the long axis of the negative liquid crystal is less than the dielectric constant of the direction vertical to the long axis. Therefore, when no vertical electrical field acts on the negative liquid crystals 14, the long axis of the liquid crystal is vertical to the substrate. When a vertical electrical field acts on the negative liquid crystals 14, the liquid crystal rotates in a specific direction under the effect of the electrical field and become vertical to the electrical field because the dielectric constant of the long axis of the liquid crystal is less. In contrast to the IPS display mode, the VA display mode does not need the rubbing procedure in the manufacturing process and thus has a great advantage in mass production.
But in contrast to the IPS display mode, the VA display mode has a severe color shift when it's viewed in a large viewing angle. Multiple solutions are provided. For example, coupling capacitor method (CC method), double TFT driving method (TT method), and charge sharing method are provided. Each of the method has its own advantages and disadvantages. But they have something in common. That is, they all divide a sub-pixel into two portions. One of the portions is called as Main portion, and the other is called as Sub portion. Usually, the Main portion is smaller than the Sub portion. This kind of design is called as 8-domain design.
The lighting point on the display panel is called as display panel lightspot, which is a physical damage of the display panel. This lightspot is formed because the inner light reflection plate is pressed by an external force or heated to slightly change its shape. As the demands of consumers are getting higher, a lightspot larger than ½ sub-pixel is unacceptable. However, in the actual manufacturing process, the lightspot is inevitable. Even the lightspot can be repaired into a normal spot, more production capacity is consumed.
The lightspot of the above-mentioned 8-domain design has its own characteristic. One condition is that the entire sub-pixel is bright. One condition is that only the Main portion of the sub-pixel is bright. One condition is that only the Sub portion of the sub-pixel is bright.
Under the condition that only the Main portion of the sub-pixel is bright, it does not influence display effects because it is smaller than ½ sub-pixel. It can be regarded as a normal spot instead of a lightspot. As shown in FIG. 2, if the Main portions of two adjacent sub-pixels are both bright, although each one of the Main portion cannot be regarded as a lightspot, they become a lightspot larger than ½ sub-pixel in horizontal because two Main portions are close to each other. This can be called as two consecutive points.